Storage tank for liquids



June 24, 1952 E. s. FRASER ETAL 2,501,270

STORAGE TANK FOR LIQUIDS June 24, 1952 E. s. FRASER ErAL 2,601,270

STORAGE TANK FOR LIQUIDS med Nov. 12, 194e s sheets-sheet 2 1, m Z J W m f m, w m @WQM M Z Q N www s z z l I 1| |I M. y a QW A ,M M m Z ,/T M S K m m f E s mwnmlwl:

June 24, 1952 Filed Nov. 12, 1946 Patented June 24, 1952 UNITED STATES PATENT OFFICE STORAGE TANK FOR LIQUIDS Edward S. Fraser and Clifford M. Orr, Chicago, Ill., assignors to Chicago Bridge & Iron Com. pany, a corporation of Illinois Application November 12, 1946, Serial No. 709,288

6 Claims. l

This invention relates to storage tanks for liquids, and more particularly to a, tank for storing volatile liquids and having a variable volumetric vapor capacity.

In the storing of volatile liquids, it is necessary to provide some accommodation for the variable volume of vapor within the tank. It is common in some installations to provide a separate breather vessel to receive expanding vapors from the tank and to return the vapors to the tank upon the contraction thereof. On other installations provision is made for the entire roof to rise and fall with changes of Vapor pressure within the tank.

We have invented, and are herein disclosing and claiming a flexible breather positioned cntirely within the tank and adapted to ilex upwardly and downwardly with variations in vapor pressure to provide a variable volumetric vapor capacity for the tank.

The inventions will be described as embodied in the accompanying drawings in which:

Fig. l is a plan view, partly broken away, of a storage tank;

Fig. 2 is a vertical section along lines 2-2 of Fig. 1;

Fig. 3 is a plan view, partly broken away of a storage tank embodying an alternative construction;

Fig. 4 is a verticall section along lines 4--4 of Fig. 3;

Fig. 5 is a plan View, partly broken away, of a storage tank showing another modification of the invention; and

Fig. 6 is a vertical section along lines 6 5 of Fig. 5.

Referring to the embodiment shown in Figs. l and 2, we show a cylindrical storage tank I having side walls I I and a top I2 provided with a screened vent I3. Secured to the upper portion of the sides of the tank is a, ilexible non-metallic seal I4 which is adapted to flex upwardly to the position shown by the solid lines in Fig. 2 under increasing vapor pressure within the tank, and to flex downwardly to the position shown by the dotted lines in Fig. 2 under decreasing vapor pressure. In its lowermost position the seal I4 rests upon the perforated support member I5. The member I is located within the tank, and positioned below the nominal high liquid level.

The ilexible seal I4 is attached to the sides of the tank, on a substantially horizontal plane located at least as low as the high liquid level. Roof supporting members I6 extend upwardly from the bottom of the tank and support the roof. These supporting members pierce the flexible seal I4 at various points, and are maintained in vaportight relationship therewith by means A oi the sleeves I'I which are secured to the supporting members I6 at I8 in vaportight relationship. The sleeves are of such length as to permit the sealing member to llex upwardly and downwardly without imposing strain upon the connection I8. A pressure-vacuum vent I9 is provided on one side of the t'ank to vent excessive pressures and vacuums. A gauge well 2li is also provided. A considerable saving of space is effected by the positioning of the perforated or permeable supporting member I5 below the highest liquid level as it is clear that less vapor storage space is required for a nearly full than for a nearly empty tank. From the construction just described, it can be seen that more vapor storage space is available when the tank is less than full than when the tank is full of liquid.

In the embodiment shown in Fig. 3, the tank I I0 is provided with sidewalls I II and a roof II2 having a portion I IZa of lesser diameter than the diameter of the tank and of generally outwardly convex shape. Secured to the extremities of the portion IIZa is a liexible sealing member IIlI which is adapted to flex upwardly and downwardly with varying vapor pressure Within the tank. The perforated or permeable support member II5 is positioned within the tank at or above the high liquid level of the tank. A screened vent I I3 is provided in the portion II2a to vent air from behind the flexible seal. Roof supporting members IIS are provided within the tank. Variations in the vapor pressure within the tank will cause the sealing member I I4 to flex upwardly or downwardly, the limit of downward travel being determined by the position of supporting member H5, and the upward travel being limited by the height of the roof portion II2a. It can be seen that the flexible sealing member in its uppermost positions (as shown by the solid lines) is backed up by the roof portion II2a land hence not subjected to tearing under excessive pressures. Pressure and vacuum vents or valves may be provided on the tank, if desired.

In the embodiment shown in Figs. 5 and 6, the tank ZIB is provided with sidewalls 2II and a roof 2I2. A screened Vent 2I3 is positioned in the top of the roof portion and a flexible seal 2M is attached on a substantially horizontal plane to the roof 2 I 2. As shown in the drawings, the nexible seal has a lesser cross sectional diameter than that of the tank. In the particular embodiment shown in Figs. 5 and 6, the llexible seal 2M is annular in shape and is secured to the roof portion at its outer periphery 220 and to a substantially circular metallic plate 22| at its inner periphery 222. The sealing member, comprising the flexible portion 2| 4 and the central portion 22|, is free to flex upwardly and downwardly with variations in vapor pressures within the tank, the downward movement being Vinsured by the weight of the member 22 I In the uppermost position shown by the solid lines in Fig. 6, the flexible portion of the seal is backed up by the roof and the edges of the central metallic portion 22| also rest against the roof, thereby preventing excessive pressures from tearing or rupturing the seal. The sealing member is supported in its lowest position (as shown by the dotted lines in Fig. 6) by a permeable supporting member 2 l5 positioned within the tank at or above the high liquid level thereof.-

In the two embodiments shown in Figs. 4 and 6, the seal is supported at or above the high liquid level `by the supporting members H5 and Zie. While such positioning of the supporting members necessitates additional vapor storage space as contrasted with the embodiment shown in Fig. 2, the sealing member is less likely to deteriorate from contact with the liquid within the tank.

While the invention may be susceptible to various modifications and alternative constructions, it `has herein been shown and described in its preferred embodiments. It is not intended, however, that the invention' is to be limited thereby to the specific constructions disclosed. On the contrary, it is intended to cover all modications and alternative constructions falling within the I spirit and scope of the invention as defined in theappended claims.

We claim:

1. Ina liquid storage tank having a shell and a dome-shaped weather roof thereover, breather means comprising: a flexible annular non-metallic diaphragm within said tank having its outer marginal edge secured to the upper portion of the tank on a substantially horizontal plane, said plane being at least as high as the high liquid 45 3. The sealing means of claim 1 in which said diaphragm is secured at itsr center to a substantially circular metallic member.

4. In a liquid storage tank having a shell and a dome-shaped weather roof thereover, at least a portion of said roof being convex outwardly, an annular flexible diaphragm having its outer marginal edge attached to said roof on a substantially horizontal plane, said diaphragm having a cross-sectional diameter less than that of the tank and being adapted to flex upwardly within said convex portion to provide a variable volumetric Vapor capacity for said tank, and a fixed dish-shaped vapor permeable supporting member secured at said horizontal plane Within said tank adapted to support said diaphragm above the high liquid level of said tank when said diaphragm is in its lowest position.

5. In a liquid storage tank having a shell and a weather roof thereover, breather means comprising: a flexible diaphragm within said tank attached to the shell on a horizontal plane of attachment, said plane being at least as low as the high liquid level of said tank, said diaphragmV being suspended within the tank substantially in the form of a catenary and being adapted to flex upwardly and downwardly to provide a variable volumetric vapor capacity for said tank, and a xed liquid permeable supporting member within said tank adjacent the upper portion thereof and adapted to support said diaphragm below the high liquid level of said tank when said diaphragm is in its lowest position.

6. The breather means of claim 5 including roof supporting members within said tank secured to the bottom thereof and to the roof, said roof supporting members piercing said ilexible diaphragm and being secured thereto in vaportight relationship.

EDWARD S. FRASER. CLIFFORD M. ORR.

REFERENCES CITED The following references are of record in the iff-.le of this patent:

UNITED STATES PATENTS Jackson Apr. l, 1947 

